1. Field of the Invention
The present invention is directed to an actuation device for a friction clutch which is arranged in the drivetrain of a motor vehicle between a drive unit and a transmission, comprising a pressure medium force cylinder arrangement by means of which the friction clutch can be actuated via a release member, a measuring arrangement which detects an actual disengagement or release, a control/regulating valve arrangement which is connected with a pressure medium source, with a pressure compensation opening or a pressure compensation reservoir and with the pressure medium force cylinder arrangement and which is controllable electrically, by means of which control/regulating valve arrangement the pressure medium force cylinder arrangement can be actuated depending on the actual release and on a reference release which can be predetermined.
2. Description of the Related Art
An actuation device of the type mentioned above with an electrically controllable control/regulating valve arrangement is known, for example, from EP 0 371 975 B1. Other actuation devices of this type are known from DE 197 16 600 A1 whose disclosure is incorporated in the disclosure of the present application by reference.
It is known, per se, from DE 197 16 600 A1 to provide a characteristic line which correlates a reference release to a command variable so that, proceeding from a disengaged state, a fast closing of the clutch up to the slip point is achieved on one hand and a spread between the slip point and the engaged position is achieved on the other hand with a view to a sensitive engagement.
In contrast, according to a first aspect of the invention in an actuation device of the type mentioned above with an electrically controllable control/regulating valve arrangement, the control/regulating valve arrangement can be actuated depending on the actual release, on a command variable which can be predetermined electrically, and on a characteristic line which converts the command variable into the reference release. Several different characteristic lines are provided which can be selectively activated depending on a desired driving behavior and/or depending on driving states and/or operating states of the vehicle for actuating the valve arrangement.
It is suggested according to the invention that the characteristic lines are switched over in a certain way in order to provide specific characteristic line shapes for different operating states or driving states. The switching over of characteristic lines makes it possible to optimize the operating behavior of the actuation device with respect to different objectives. On the one hand, startup comfort can be increased and, on the other hand, clutch wear can be minimized in order to prolong the life of the clutch, for instance. The characteristic lines may be customer-specific characteristic lines, that is, for example, characteristic lines provided by an automobile manufacturer in an actuation device specific to a clutch manufacturer or the like, for example, by outfitting the control/regulating electronics with an EPROM containing the characteristics in digital form.
For example, a startup and/or maneuvering characteristic line with a spread slip point associated with a startup and/or maneuvering situation can be provided in order to facilitate startup and/or maneuvering. Another possibility would be to provide an upshift and/or downshift characteristic line without a spread slip point associated with an upshift and/or downshift situation in order to minimize slip states of the friction clutch with respect to time and accordingly to counteract clutch wear.
It is possible for at least one of the characteristic lines to be activated manually by means of a selector switch, for example, in order to enable the driver to choose between a more comfortable clutch actuation response or a clutch actuation response better suited to recreational driving. Further, it is particularly preferable to provide means for detecting the driving status and/or means for detecting the operating state which switch between several characteristic lines in order to activate an associated characteristic line depending on the detected driving state and/or operating state.
A friction clutch to be actuated by means of the actuation device mentioned in the beginning is generally arranged in a housing, often called a bell housing or a housing cover, between the transmission and the drive unit and can be formed at least partially by wall portions of the drive unit housing and/or of the transmission housing. In this case, it is advisable to arrange the pressure medium force cylinder arrangement in the housing cover as well; it has proven advantageous when the pressure medium force cylinder arrangement comprises a ring cylinder which encloses, preferably concentrically, a torque transmission shaft, especially a transmission input shaft. In this case, it is advisable in many respects to arrange a constructional unit at the pressure medium force ring cylinder and to connect a ring cylinder space of the pressure medium force ring cylinder to the control/regulating valve arrangement via at least one connection of the constructional unit. However, this is problematic in that the pressure medium force ring cylinder is exposed in the housing cover to comparatively high thermal loading which may not necessarily be withstood by the sensitive components of the actuation device.
In order that the thermal loading can at least be reduced with respect to the constructional unit and heat-sensitive components or a heat-sensitive region of the constructional unit, it is suggested according to a second aspect of the invention that the constructional unit has a thermal dividing or separating layer which is arranged between a heat-sensitive region of the constructional unit and a fastening region by means of which the constructional unit is arranged at the pressure medium force ring cylinder. Components and parts which need not be arranged in immediate contact with the pressure medium force ring cylinder can accordingly be arranged so as to be thermally isolated from the pressure medium force ring cylinder.
For example, the control/regulating valve arrangement can be integrated in the constructional unit. The separating layer could then be arranged between the control/regulating valve arrangement and the fastening region.
Further, the measuring arrangement can be integrated in the constructional unit. The measuring arrangement may possibly be arranged in a region of the constructional unit located between the fastening region and the separating layer to the extent that, following the measurement principle on which the measuring arrangement is based and the manner in which the measuring arrangement is coupled to an element whose position, for example, represents the actual release, the measuring arrangement must be arranged in the immediate vicinity of the pressure medium force cylinder arrangement. Also, the control/regulation valve arrangement and the measuring arrangement can be embodied in a common constructional unit structure.
In order to substantially reduce the thermal loading for the heat-sensitive region of the constructional unit (for example, the control/regulating valve arrangement) or to eliminate any thermal loading, the heat-sensitive region of the constructional unit (which can include the control/regulating valve arrangement) can project out of the latter through a housing cover opening. In this connection, it is particularly advisable when the wall of the housing cover has a recessed wall part in which the housing cover opening is provided, the housing cover opening being disposed at an inner end portion of a surrounding wall portion of the recessed wall part.
In this way, it can be achieved that at least the heat-sensitive area of the constructional unit is shielded relatively well against the thermal loading inside the housing cover and heat occurring in the hear-sensitive area of the constructional unit or heat which is transferred to the constructional unit through heat transfer can be discharged to the outside comparatively effectively. In this case, the thermal separating layer of the constructional unit can even be dispensed with under certain circumstances. According to a third aspect, the invention provides a corresponding actuation device. Preferably, however, a thermal separating layer is provided, which can be particularly effective when it is arranged roughly at the height of the wall portion defining the housing cover opening.
According to a fourth aspect, it is suggested in connection with the constructional unit arranged at the pressure medium force ring cylinder that a separate valve constructional unit having the control/regulating valve arrangement is arranged outside the housing cover, possibly at an outer side of the housing cover, wherein the valve constructional unit is connected with the constructional unit arranged at the pressure medium force ring cylinder via at least one connection hose or connection pipe and/or at least one electric connection cable.
According to this inventive suggestion, heat-sensitive components, especially the control/regulating valve arrangement, can be arranged outside the housing cover in order to reduce thermal loading thereon. Nevertheless, as with the actuation devices according to the first, second and third aspects, it is possible to integrate components serving to control the pressure medium force cylinder arrangement, especially the control/regulating valve arrangement and the measuring arrangement enabling exact positioning, in one or more constructional units resulting in a simple, economical and manageable construction and enabling a simple, economical assembly. When a constructional unit and a separate valve constructional unit (in which other components can also be integrated) are provided, the expenditure on assembly is only slightly higher compared with integration of the control/regulating valve arrangement in the constructional unit arranged at the pressure medium force ring cylinder, this slight increase being more than offset by the advantages achieved with respect to the reduced or even eliminated thermal loading of the control/regulating valve arrangement. Beyond this, the valve constructional unit is substantially more accessible because of its arrangement outside the housing cover, so that maintenance is substantially facilitated. As a rule, the measuring arrangement can be advantageously integrated in the constructional unit arranged at the pressure medium force ring cylinder.
It should be mentioned with regard to the actuation devices according to all of the aspects discussed above that the control/regulating valve arrangement can comprise a proportional solenoid valve which, as such, need be the only valve of the control/regulating valve arrangement. As a rule, the pressure medium force cylinder arrangement is a pneumatic force cylinder arrangement. In this case, the pressure medium force ring cylinder is a pneumatic force ring cylinder.
For an actuation device for a friction clutch which is arranged in the drivetrain of a motor vehicle between a drive unit and a transmission, comprising a pressure medium force cylinder arrangement by means of which the friction clutch can be actuated via a release member, a measuring arrangement which detects an actual release, a control/regulating valve arrangement which is connected with a pressure medium source, with a pressure compensation opening or a pressure compensation reservoir and with the pressure medium force cylinder arrangement and which is controllable electrically, by means of which control/regulating valve arrangement the pressure medium force cylinder arrangement can be actuated depending on the actual release and on a reference release which can be predetermined, it is suggested, according to another aspect, that the control/regulating valve arrangement comprises a valve operable in a mode which is associated with an engagement actuation as well as in a mode associated with a disengagement or release actuation and which has a first valve connection connected with the pressure medium force cylinder arrangement, a second valve connection connected with the pressure source, and a third valve connection which is connected with the pressure compensation opening and pressure compensation reservoir and which can be changed to a valve state connecting the first and second valve connections and to a valve state connecting the first and third valve connections.
Compared with the arrangement known from EP 0 371 975 B1, in which the control/regulating valve arrangement is formed by four switching valves, two of which are associated with an engagement actuation while the other two are associated with a release actuation, the quantity of structural component parts can be appreciably reduced according to the inventive suggestion with a consequent reduction in cost and simplification of the arrangement. The simplification of the arrangement results in advantages with respect to operating reliability.
The valve can be changed to a valve state in which the first valve connection is connected neither with the second valve connection nor with the third valve connection. The valve is preferably changed between valve states by means of electric control, wherein it can be provided that the valve occupies a determined valve state without electric control, preferably that valve state in which the first valve connection is connected neither with the second nor with the third valve connection.
A particularly preferred embodiment form is distinguished by the fact that the valve is a proportional solenoid valve. A large signal behavior which is substantially improved compared with the use of one or more switching valves is therefore achieved because a proportional valve can be opened very far, resulting in a large flow cross section for the pressure medium, particularly compressed air. With respect to small signal behavior, values are achieved which are as good as when one or more switching valve are provided.
It is not out of the question that the control/regulating valve arrangement comprises one or more additional valves apart from the valve mentioned above which is associated with the engagement actuation and release actuation. However, with respect to the reduction in structural component parts and the simplicity of the arrangement, it is preferable that the control/regulating valve arrangement has only this one valve.
The valve arrangement and the measuring arrangement can be part of a unit arranged at a pressure medium force ring cylinder of the pressure medium force cylinder arrangement, wherein the unit preferably has a pressure medium connection which is detachably connected with the pressure medium source. Further, the unit can have a pressure medium connection which is detachably connected to the pressure compensation opening and pressure compensation reservoir or can have the pressure compensation opening itself. Further, the unit preferably comprises electric power supply connections and/or control connections comprising at least one electric plug-in connector. The plug-in connector may be constructed as a plug strip or the like arranged at a housing of the unit. However, a solution wherein the plug-in connector is arranged at a connection cable or connection cable tree which is guided out of the unit and has a plurality of connection lines is preferred.
Otherwise, it is possible to construct the actuation device such that it corresponds extensively to the actuation device known from EP 0 371 975 B1.
According to another aspect, however, it is suggested with respect to the actuation device mentioned above that a release piston of the pressure medium force cylinder arrangement which is arranged, along with the friction clutch, in a housing cover serves as a release member and acts directly on a release bearing associated with the friction clutch. By dispensing with a clutch release lever or the like which is provided in the actuation device of EP 0 371 975 B1, it is possible that the measuring arrangement can detect the actual release substantially more directly or can control or regulate the position of a pressure plate of the clutch substantially more directly. The inventive idea is based on the thought that any intermediate components or transmission members between the pressure medium force cylinder arrangement and release bearing are disadvantageous with respect to idle times, phase displacements, hysteresis effects and so on, and can lead to defects in the dynamic behavior of the actuation device and, at worst, to instability and vibrations.
The actuation device can advantageously be constructed in such a way that the control/regulating valve arrangement can be actuated via control/regulating electronics depending on the actual release and on a characteristic line converting an electrically presettable command variable into the reference release.
The invention is further directed to a set for providing at least one actuation device for a friction clutch arranged in the drivetrain of a motor vehicle between a drive unit and a transmission. The actuation device which can be provided based on the set comprises a pressure medium force cylinder arrangement by means of which the friction clutch can be actuated via a release member, a measuring arrangement which detects an actual release, a control/regulating valve arrangement which is connected with a pressure medium source, with a pressure compensation opening or a pressure compensation reservoir and with the pressure medium force cylinder arrangement, by means of which control/regulating valve arrangement the pressure medium force cylinder arrangement can be actuated depending on the actual release and on a reference release which can be predetermined. A constructional unit is arranged at a pressure medium force ring cylinder of the pressure medium force cylinder arrangement by means of a standard interface arrangement, wherein a ring cylinder space of the pressure medium force ring cylinder is connected to the control/regulating valve arrangement via at least one connection of the constructional unit. The actuation device can be, for example, an actuation device according to one of the aspects discussed in the preceding, including the further developments mentioned above.
With respect to increased effectiveness and productivity in the development and production of an actuation device of this type and/or with respect to economizing on storage costs, it is suggested according to another aspect of the invention that the set comprises at least the following components: at least one pressure medium force ring cylinder or a group of several different kinds of corresponding pressure medium force ring cylinders having a connecting and fastening area serving as a standard interface for fastening an associated constructional unit by means of a standard interface arrangement which comprises the connecting and fastening area as well as a connecting and fastening area of the constructional unit used as standard interface and/or a connecting and fastening adapter, at least one constructional unit or a group of several different types of constructional units having at least one connection which can be arranged, preferably in a detachable manner, at the pressure medium force ring cylinder by means of the standard interface arrangement, wherein a ring cylinder space of the pressure medium force ring cylinder can be connected to an associated control/regulating valve arrangement via a connection, and, if desired, at least one connecting and fastening adapter associated with a determined type of constructional unit of the group for arranging a constructional unit of this type at the pressure medium force ring cylinder by means of the standard interface arrangement, wherein the set comprises at least two pressure medium force cylinders of different types and/or at least two constructional units of different types.
According to the invention, a standard pressure medium force ring cylinder (release cylinder), for example, can be used for different types of drivetrains or different use situations by combining it with a constructional unit of the group which matches the type of drivetrain or use situation. For example, different automating devices for automating clutch actuation can be used, namely, with the same type of pressure medium force ring cylinder. This is particularly advantageous because the pressure medium force ring cylinder is a component which is to be optimized with respect to wear and which is complicated to test. A type of pressure medium force ring cylinder which is tested and meets requirements in a dependable manner can then be used for different drivetrains or different applications; adapting to the drivetrain or to the use situation and/or adapting for the sake of meeting automation requirements can then be carried out by selecting an appropriate type of constructional unit having at least one connection. By providing a fastening adapter, it is possible to combine a pressure medium force ring cylinder and a constructional unit having the at least one connection, whose standard interfaces themselves do not fit together.
Conversely, however, according to the inventive idea, a type of constructional unit can also be combined selectively with a pressure medium ring cylinder of a matching type from the group of different ring cylinders (which have different diameters or pressure medium volumes, for example).
The pressure medium force ring cylinder preferably has at least one fastening pin which can be made to engage with associated constructional units of the group and/or with at least one connecting and fastening adapter. Further, the pressure medium force ring cylinder can have at least one pressure medium inlet nipple and/or outlet nipple which can be made to engage with associated constructional units of the group and/or with at least one associated connecting and fastening adapter and by which the ring cylinder space of the pressure medium force ring cylinder can be connected to an associated control/regulating valve arrangement.
At least one of the constructional units can comprise a measuring arrangement which is integrated therein and which can preferably be brought into a measuring engagement with a ring piston of the pressure medium force ring cylinder in order to detect the actual release. Further, at least one of the constructional units can comprise a control/regulating valve arrangement which is integrated therein. It is particularly advisable when at least one of the constructional units comprises a control/regulating valve arrangement integrated therein and a measuring arrangement integrated therein, wherein the measuring arrangement can preferably be brought into a measuring engagement with a ring piston of the pressure medium force ring cylinder in order to detect the actual release.
Several constructional units can differ with respect to the type of measuring arrangement or the design of the measuring arrangement, for example, their coupling to the release member, and/or with respect to the type of control/regulating valve arrangement or the design of the control/regulating valve arrangement.
Further, several constructional units can differ from one another with respect to the construction of electric connections and/or pressure medium connections.
Several constructional units can differ with respect to their outer form or external configuration in order to enable matching with respect to the available installation space in a housing cover in which the friction clutch and pressure medium force ring cylinders are received.
At least one of the constructional units can have a thermal separating layer arranged between a heat-sensitive area of the constructional unit and its connecting and fastening area.
The set can have at least one separate valve constructional unit, in which a control/regulating valve arrangement is integrated and which is provided for arrangement outside a housing cover receiving the friction clutch and pressure medium force ring cylinder, possibly at the outer side of the housing cover, wherein at least one of the constructional units of the group is associated with the valve constructional unit and is connected or can be connected with it via at least one connection line, hose line or pipe line and/or at least one electric connection cable. The set can comprise a group of different types of corresponding valve constructional units.
The invention is further directed to an actuation device which can be provided by means of a set according to the invention.
The invention is further directed to a motor vehicle drivetrain comprising a drive unit, a transmission and a friction clutch arranged between the drive unit and the transmission, and comprising an actuation device as was described above.
Other objects and features of the present invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the invention, for which reference should be made to the appended claims. It should be further understood that the drawings are not necessarily drawn to scale and that, unless otherwise indicated, they are merely intended to conceptually illustrate the structures and procedures described herein.